Over medium flame in a pan, heat 2 tsp oil.
Add the black gram and stir-fry till it is golden. Turn off the heat.
Add the split red chillies and stir-fry for a few seconds.
When it cools down a bit (but is still warm), add the mint leaves and mix well.
With a little water, grind together the fried black gram, mint leaves, chillies, tamarind, turmeric and salt to a coarse paste.
Transfer the mixture into a bowl and set aside.
Heat 1 tsp oil.
Add the mustard seeds and wait till they splutter.
Add the mustard seeds to the mint chutney.
Serve with warm rice and ghee.